How many Berghia slugs do I need?

One of the most common questions when dealing with an Aiptasia infestation is: How many Berghia nudibranchs (Berghia stephanieae) do I actually need for my aquarium? Since these nudibranchs are pure dietary specialists and hunt in groups, the correct number depends heavily on the degree of infestation.

Here is our practical guide for orientation:

Light Infestation (Individual, visible Aiptasia)
If you've only discovered scattered Aiptasia (approx. 5 to 10) in your reef, the infestation is still in its early stages.
• Recommendation: At least 3 to 5 nudibranchs.
• Reason: The animals need to be able to find each other in the aquarium to reproduce and establish a stable population before the Aiptasia get out of control.

Moderate Infestation (Aiptasia visible on several rocks)
Do you already see small colonies of Aiptasia (approx. 10 to 50) on various rocks? Then a small group is no longer enough, as the Aiptasia will multiply faster than the nudibranchs can eat them.
• Recommendation: 5 to 10 nudibranchs (our 5-pack or 10-pack is optimal).

Heavy Infestation / True Plague (Dozens of Aiptasia, corals already being stung)
If the live rock is heavily overgrown with Aiptasia and the pests are already bothering your corals, you need to react quickly and with an "army."
• Recommendation: 15 to 25 nudibranchs (Here, it's best to go for our discounted 15-pack).

Rule of thumb by aquarium size:
• Nano aquariums (up to 100 liters): approx. 3 – 5 Berghia nudibranchs
• Medium aquariums (100 to 300 liters): approx. 5 – 10 Berghia nudibranchs
• Large aquariums (over 300 liters): approx. 15+ Berghia nudibranchs

Why an insufficient stocking often fails:
Berghia nudibranchs are small and nocturnal. If you put too few nudibranchs in a large aquarium, there is a high probability that they will not find each other, will not lay eggs, and the Aiptasia reproduction will simply be faster than the nudibranchs' appetite.

 Therefore, rely on a sufficiently large group from the start to permanently break the infestation.